Photovoltaic systems are increasingly used to produce electricity from sunlight. Beside wind power, a very high economic importance is especially attached to photovoltaics, since it provides a still largely untapped potential. For example it is readily possible to feed the generated but not requested current into the electricity grid or to charge batteries for later use.
Unlike wind power stations, photovoltaic systems are lightweight, compact, easy to handle, and virtually maintenance-free. They can be configured much more flexible than wind power stations and thus offer themselves as a flexible and inexpensive isolated solution. So far, photovoltaic modules were mainly placed on roofs or in the open at suitable areas. However, not all potential users have available such a roof or suitable area. Also, the ratio of roof surface to living surface may be low, so that only a small power collecting surface is facing a high demand of electricity.
Although the photovoltaic modules could be attached to building facades, this is sometimes not desirable since the photovoltaic modules might have a negative effect on the appearance of the building, for aesthetic reasons. Additionally, the front facade is usually dominated by windows. A large portion of the useful light gathering or power collecting surface therefore remains unexploited.
A solution to this problem is provided by the use of transparent photovoltaic modules. Not only may such modules be attached visually neutral on or to facades, but may even be attached to or accommodated between window glass panes, especially in the space between double-walled insulating glass. These photovoltaic modules now do no longer disturb the outer appearance of the building, as they are largely transparent. Especially in glazed buildings with many floors this presents a huge economic and energetic potential. Besides, such modules do not only generate electricity, but also serve as a sunscreen, privacy screen, and/or anti-glare screen.
Usually, conventional photovoltaic modules are connected and wired on their rear face using a junction box. Patent application DE 10 2008 022 297 A1 describes such a junction box for solar modules and methods for mounting it to the modules. According to this document, with the box mounted, the flat-ribbon cables emanating from the photovoltaic module are pressed into grooves provided therefor, the cables establishing an electrical contact with connectors which are attached to the housing, via contact terminals. The electrical connection between the flat-ribbon conductors and the contact terminals is produced either by means of contact clamps, or by soldering or welding.
Patent application DE 10 2007 006 433 A1 describes a junction box for electrically connecting a solar module and a method for mounting a junction box to a solar panel. The two-part junction box is connected to a contact clamp at the rear face of the photovoltaic substrate by means of a ribbon cable which establishes an electrical contact to the photovoltaic module. This ribbon is threaded into the lower housing part. When the upper housing part is placed onto the lower housing part, suitable guide elements in the interior of the housing establish a contact between the ribbon cable and an electrical connector which protrudes from the junction box.
In case of insulating glass, especially those having a transparent semiconductor film, for example for facades, such wiring is not suitable or desirable, since such a box would have to be attached to each insulating glass pane. The contacting of the panes and the wiring between the modules would be implemented within the facade framework in order not to impair the view through the insulating glass. Also, the photovoltaic module is arranged between the insulating glass panes. Therefore, the electrical contacting of the photovoltaic module would have to be passed to the outside in complex manner, to protect the interior of the insulating glass from moisture. This requires additional components and/or increased assembly costs.
Therefore, contacting of an insulating glass on a lateral side thereof would be desirable.